Television apparatus and the like



Sept. 5, 1933. J. L. BAIRD TELEVISION APPARATUS AND THE LIKE Filed May 18, 1929 Patented Sept. 5, 1933 PATENT OFFICE TELEVISION APPARATUS AND THE LIKE John Logic Baird, London, England, assignor to Television Limited, London, England, a British Company Application May 18, 1929, Serial No. 364,177,

' and in Great Britain June 5, 1928 2 Claims. (Cl. 178-6) This invention concerns improvements in or relating to television apparatus and the like, and it has for one of its objects the reproduction or" the transmitted image in colours.

r In accordance with the invention, there are transmitted currents due to, say, two images which images may be termed the red image and the blue image, or, if a three-colour process be employed (as hereinafter more particularly described), there are transmitted currents due to three images, say, a red image, a blue image and a green image.

The currents due to these images are fed in succession on to the line and at the receiver the images are reconstituted and are presented successively to the eye of the observer.

A feature of the invention is a television or like system for the reproduction of the transmitted image in colours, comprising (a) at the transmitting station, a plurality of light-sensitive cells which differ from one another in regard to their sensitivity to different colours, together with means for effecting exploration of the object by said cells, (b) at the receiving station, a plurality of lamps each adaptedto, emit light rays corresponding in -colour to those respectively to which each cell is particularly sensitive, and (c) means (for example synchronously-operated commutator-like devices at each of said stations) for rendering operative simultaneously 3 each cell and its corresponding lamp, and for rendering operative successively the cells of the said plurality.

During exploration of the object by each cell, the object may be illuminated by light oi the colour to which that cell is particularly sensitive,

and the illumination may take the form of a Another feature of thefinvention relates to a method of exploration by overlapping parallel bands which is hereinafter more particularlyexplained. 7 I

Constructions of apparatus and methods of operation according to the invention will now be described, by way of example, with the aid of the accompanying diagrammatic drawing in wliichzv igure 1 shows apparatus at a transmitting station; r Figure 2 shows apparatus at a receiving. station;

r the disc.

Figure 3 is illustrative of a method of exploration hereinafter described.

The transmtting apparatus shown in Figure 1 comprises a rotating exploring disc 2 provided with three sets 4, 6, 8 of lenses or holes, each set being arranged as usual on a spiral curve. Light is projected from a lamp 10 on to the disc 2, and passing through the holes in the disc explores the object 12,.as the disc rotates, in a series of light spots, the spots due to each set of holes 4, 6, 8 completely traversing the object. Light-filters (not shown) are employed to cover the sets of holes 4, 6, 8. For instance, the holes of set 4 may be covered by blue light-filters supported on the disc 2, the holes of set 6 by red light-filters and the holes of set 8 by green lightfilters. Cells 14, 16, 18 sensitive, respectively, to blue, red and green light are situated Where light reflected from the object 12 will fall upon them. The current from these cells is supplied in succession toan amplifier 20 forming part of the transmission apparatus, by means of a commutator 22. This commutator has three insulated segments each of which is electrically connected, respectively, with one of three slip rings 24, and there is abrush 26 which bears upon each ring 24 and is connected by a conductor 28 with one of the cells 14, 16, 18. A brush 3O bearing on the commutator 22 is connected with the amplifier 20 by a conductor 32 and a conductor 34 serves as a connection, common to all the cells 14, 16, ,18, between those cells and the amplifier 20. The commutator 22, and the slip rings 24, rotate in synchronism with the disc 2, and for that purpose are shown as supported on the shaft 36 of In operation, while the object 12 is being explored by blue light. from the set of holes 4, the commutator 22 connects theblue-sensitive cell 14 with the amplifier 20 so that current from that cellis fed, by Way of the amplifier, to the transmitter from whence it'is transmitted by a wired or wireless connection to the receiving station. Similarly, while the object is being explored by red and by green light from the sets 6 and 8 respectively, the commutator 22 connects, in turn, the red-sensitive cell16 and the green-sensitive cell 18 with the amplifier so that currents due to these cells are transmitted, in turn, to the re ceiving station.

At the receiving'station, a disc 40 (Figure 2) is used which is similar to and revolves synlight, the lamp 46 a beam of red light, and the lamp 48 a beam of green light. These lamps are fed with current in succession synchronously with the activation of the blue-sensitive cell i l, the red-sensitive cell 16 and the green-sensitive cell 18 at the transmitting station. To effect this, the apparatus shown includes a three-segment commutator 50 and three slip rings 52, which are similar to the commutator 22 and rings 2% at the transmitting station, and are rotated synchronously with the disc 40 by being mounted upon the shaft of that disc. The slip rings 52 are connected respectively with the lamps i l, as, 48 each by a brush 56 and a conductor 58 and the lamps are connected by a conductor 60, common to all of them, with an amplifier 62 (forming part of the receiving apparatus) which in turn is connected by a conductor 64 with a brush 66 that bears upon the commutator 50.

In operation, the receiving disc 40 and he parts that rotate with it, are run in synchronism with and in phase with the corresponding parts at the transmitting station, with the result that when the object 12 is being explored by light spots from one or other of the sets of holes l, 6, 8, current modulated in accordance with the activation of the appropriate cell 14, 5 or 18 varies the light emitted by the corresponding lamp i l, 46 or 4:8 which at that time is in circuit due to the action of the commutator 50. Thus, at the receiving station there will be presented to the observer 42 a series or" blue, red and green images of the object 12-, but these images will be presented at a rate such that persistency or" vision causes the three images as seen by the observer to be blended into a single image which has the same or approximately the same colours as those of the object 12, Due to the lateral separation of lamps 44, 46 and as shown in the drawing, it may be'desirable to place a translucent screen 68 adjacent the disc so to facilitate viewing all three of the colored images through the apertures in the disc 4 .0. The sameeifcct, however, may be obtained in other wa s. Thus, by suitable optical means as, for instance, transparent reflectors the light from the three lamps may be made to appear as if coming from the same position. Another method of accomplishing the same result is to arrange three lamps, each giving a luminous discharge of the proper color one behind the other, the light from the two rearmost lamps passing through the lamp or lamps in front. 7

When using lamps emitting different colours as above mentioned, the sets of holes or lenses in the disc do need not be provided with the appropriate coloured light-iilters, but these may be employed, if desired.

Figure 3 illustrates a method of exploration having for its object an improvement in the definition of the image without loss of brilliance in the image. According to this method, explora- 'tion by the light-apertures of the exploring device plores a band 72 which overlaps the band to an extent of some two-thirds of its width, the third light-aperture next explores a band 74 which overlaps the band 72 some two-thirds and the band 70 some one-third of the band-with, and so on. When the exploring device takes the form of a rotating disc having a spiral arrangement 01 than one set of light-apertures are provided on the exploring disc and each set is arranged on a spiral curve, as in the examples hereinbeiore de scribed, the apertures of each set may be arranged as usual to explore parallel non-overlapping bands, but the sets of apertures following the leading set will each be displaced as a whole, say nearer to the centre of the disc, so that each aperture of following sets will explore part of the band explored bythe corresponding aperture of the immediately-preceding set.

I claim:

1. A system of television for the reproduction of transmitted images in colors, comprising a transmitting station and a receiving station, means at said transmitting station comprising a plurality of light sensitive cells differing from one another in regard to their sensitivity to different colors, said cells being positioned with respect to an object to receive reflected light therefrom, scanning means for said object comprising a disc, having a plurality of series of apertures, each series being adapted to traverse a beam of light over substantially the entire exposed surface of said object, each beam of light being of a color par 'cularly effecting one of said light cells, a plurality of lamps at said receiving station, each bein adapted to emit light rays corresponding in color to those respectively to which each cell is particularly sensitive, and means for rendering operative simultaneously each cell and its corresponding lamp, and for rendering operative successively the cells of the said plurality,

2. A system television for the reproduction of transmitted in in colors, comprising a trans mitting station and a receiving station, means at said transmitting station for successively traver ing an object by a plurality of spots of different colored light within the persistency of vision, each spot tracing a series of contiguous paths across the surface of said object, a plurality of light sensitive cells differing from one another as regards their sensitivityto diiierent colors, each cell being particularly sensitive to one of said spots of differently colored li ht, means causing each cell to be functionally operative during the traversing of the ohject by its corresponding spot of light, a plurality of means said receiving station, each being adapte to emit light rays corresponding in color to those respectivelyto which each cell is particularly sensitive and means for rendering operative each cell and its corresponding light emitting means.

JOHN LOGIE BAIED. 

